1. Field of the Invention
The present invention is directed to a heart pacemaker system including a pacemaker housing with a connector portion, and an electrode line having a proximal end introduced into the connector portion, and a distal end having an electrode head attachable to the part of a user.
2. Description of the Prior Art
The goal of a heart pacemaker system is to produce a durable and reliable electrical connection between the pacemaker and the heart of a patient. Thus, a faultless mechanical and electrical connection between the connector portion of the pacemaker and the proximal end of the electrode line must be present. Moreover, the distal end of the electrode line must be anchored such that the electrode head can reliably transmit a stimulation pulse to the heart. The electrode line must also be shaped such that, in certain instances, portions of the electrode line and the electrode head lie against specific locations of the wall of the heart. The electrode head and the electrode line may also have a sensing function, so that heart activities can be sensed.
Threaded connections are frequently used for connecting the electrode line to the pacemaker housing. A pin plug of the electrode conductor is introduced into the pacemaker connector in the system disclosed in U.S. Pat. No. 4,226,244, and is secured therein with set screws. To prevent body fluid from penetrating into the connection, cover caps are subsequently introduced into the screw openings. A disadvantage of this system is the use of a plurality of parts in order to produce a connection. Moreover, the extremely small parts can easily be lost.
Fixing means are also necessary for attaching the electrode head at the distal end of the electrode line to the wall of the heart. Such an electrode line is disclosed in U.S. Pat. No. 3,939,843, wherein bristles bent backwardly are used as the fixing means. The bristles are bent and retained with a hold-down means at the insulation during introduction of the electrode line into a vein, so as to prevent damage to the wall of the vein. The hold-down means is retracted after the electrode head has been introduced, thereby releasing the bristles, which engage the trabeculae after the insertion. The electrode head is thus held at a desired location. The hold-down means is an additional part of the electrode line, thereby making the pacemaker electrode more expensive.
In electrode lines having traumatic fixing means, such as screws or wires, the electrode lines are often fashioned such that the fixing means are received in a hollow protective cylinder during the introduction process. The fixing means are displaceably seated such that a mandrin, guided inside the electrode line, forces the screw or wire out of the hollow cylinder after the electrode head has been introduced. Such a heart pacemaker electrode is disclosed in U.S. Pat. No. 4,280,512. If the mandrin has been incorrectly positioned during the introduction phase of the electrode to such a degree that the fixing means are entirely or partially exposed, damage to the vessel wall will result during introduction of the lead.
If an electrode line is to be introduced into the right atrium of the heart, it may be pre-formed into a J-shape as disclosed in German OS 25 06 694. In order to straighten the J-shaped section of the electrode line during introduction through a vein, a probe guide, which is somewhat thicker than a standard mandrin, is used. This makes the overall electrode line relatively stiff, which may cause difficulties during the introduction phase.